I have an image and I'd like to add a rollover effect to it
so that a user can click on it as is common in many HTML pages.
However the redraw is extremely jerky. It looks as if it were
deleting the component (which pulls all the elements underneath it
up on the window) and then adding it back with the new image (which
pushed all the elements back down again). This is done very quickly
and looks very unprofessional. How do I do this in a way that
avoids this kind of jerkiness?

The problem is that when you change the source property on an
Image object, it makes another HTTP call to get the new image. It's
not smart enough to cache the bitmap data. You can fix the problem
by using Eli Greenfield's SuperImage instead of Image.